A rotation-rate sensor is discussed in German patent document no. 199 45 859. This rotation-rate sensor, however, has a relatively low working frequency.
In the case of the rotation-rate sensor having a rotary oscillator produced using surface micromechanics, the rotary oscillator or the centrifugal mass is mechanically centrally connected to the substrate via an X-shaped spring at one point. A working frequency is established based on the X-shaped spring and the mass of the rotary oscillator. To increase the working frequency with respect to the rotation-rate sensor from the related art, the spring arms of the X-shaped spring would either need to be widened or shortened. Naturally, a combination of the two measures is also conceivable.
However, these measures may result in the problem that the oscillation amplitude would be decreased and the stretching of the spring material would be increased. The decrease in the oscillation amplitude disadvantageously decreases the sensor sensitivity. The increase in the stretching of the X-shaped spring material may result in the spring material breaking. In addition, the non-linearity of the spring stiffness increases over the deflection if the spring length is shortened while the oscillation amplitude remains constant.
For stable sensor operation, the non-linearity is to be kept as minimal as possible since there is otherwise the risk of non-linear collapse (two stable working points).